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<div class="refentry" title="pluck">
<a id="pluck"></a>
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<h2>
<span class="refentrytitle">pluck</span>
</h2>
<p>pluck —
Produces a naturally decaying plucked string or drum sound.
</p>
</div>
<div class="refsect1" title="Description">
<a id="idp36517672"></a>
<h2>Description</h2>
<p>
Audio output is a naturally decaying plucked string or drum sound based on the Karplus-Strong algorithms.
</p>
</div>
<div class="refsect1" title="Syntax">
<a id="idp36518392"></a>
<h2>Syntax</h2>
<pre class="synopsis">ares <span class="command"><strong>pluck</strong></span> kamp, kcps, icps, ifn, imeth [, iparm1] [, iparm2]</pre>
</div>
<div class="refsect1" title="Initialization">
<a id="idp36528848"></a>
<h2>Initialization</h2>
<p>
<span class="emphasis"><em>icps</em></span> -- intended pitch value in Hz, used to set up a buffer of 1 cycle of audio samples which will be smoothed over time by a chosen decay method. <span class="emphasis"><em>icps</em></span> normally anticipates the value of <span class="emphasis"><em>kcps</em></span>, but may be set artificially high or low to influence the size of the sample buffer.
</p>
<p>
<span class="emphasis"><em>ifn</em></span> -- table number of a stored function used to initialize the cyclic decay buffer. If <span class="emphasis"><em>ifn</em></span> = 0, a random sequence will be used instead.
</p>
<p>
<span class="emphasis"><em>imeth</em></span> -- method of natural decay. There are six, some of which use parameters values that follow.
</p>
<div class="orderedlist">
<ol class="orderedlist" type="1">
<li class="listitem">
<p>
simple averaging. A simple smoothing process, uninfluenced by parameter values.
</p>
</li>
<li class="listitem">
<p>
stretched averaging. As above, with smoothing time stretched by a factor of <span class="emphasis"><em>iparm1</em></span> (>=1).
</p>
</li>
<li class="listitem">
<p>
simple drum. The range from pitch to noise is controlled by a 'roughness factor' in <span class="emphasis"><em>iparm1</em></span> (0 to 1). Zero gives the plucked string effect, while 1 reverses the polarity of every sample (octave down, odd harmonics). The setting .5 gives an optimum snare drum.
</p>
</li>
<li class="listitem">
<p>
stretched drum. Combines both roughness and stretch factors. <span class="emphasis"><em>iparm1</em></span> is roughness (0 to 1), and <span class="emphasis"><em>iparm2</em></span> the stretch factor (>=1).
</p>
</li>
<li class="listitem">
<p>
weighted averaging. As method 1, with <span class="emphasis"><em>iparm1</em></span> weighting the current sample (the status quo) and <span class="emphasis"><em>iparm2</em></span> weighting the previous adjacent one. <span class="emphasis"><em>iparm1 + iparm2</em></span> must be <= 1.
</p>
</li>
<li class="listitem">
<p>
1st order recursive filter, with coefs .5. Unaffected by parameter values.
</p>
</li>
</ol>
</div>
<p>
</p>
<p>
<span class="emphasis"><em>iparm1, iparm2</em></span> (optional) -- parameter values for use by the smoothing algorithms (above). The default values are both 0.
</p>
</div>
<div class="refsect1" title="Performance">
<a id="idp36569512"></a>
<h2>Performance</h2>
<p>
<span class="emphasis"><em>kamp</em></span> -- the output amplitude.
</p>
<p>
<span class="emphasis"><em>kcps</em></span> -- the resampling frequency in cycles-per-second.
</p>
<p>
An internal audio buffer, filled at i-time according to <span class="emphasis"><em>ifn</em></span>, is continually resampled with periodicity <span class="emphasis"><em>kcps</em></span> and the resulting output is multiplied by <span class="emphasis"><em>kamp</em></span>. Parallel with the sampling, the buffer is smoothed to simulate the effect of natural decay.
</p>
<p>
Plucked strings (1, 2, 5, 6) are best realized by starting with a random noise source, which is rich in initial harmonics. Drum sounds (methods 3, 4) work best with a flat source (wide pulse), which produces a deep noise attack and sharp decay.
</p>
<p>
The original Karplus-Strong algorithm used a fixed number of samples per cycle, which caused serious quantization of the pitches available and their intonation. This implementation resamples a buffer at the exact pitch given by <span class="emphasis"><em>kcps</em></span>, which can be varied for vibrato and glissando effects. For low values of the orch sampling rate (e.g. <span class="emphasis"><em>sr</em></span> = 10000), high frequencies will store only very few samples (<span class="emphasis"><em>sr / icps</em></span>). Since this may cause noticeable noise in the resampling process, the internal buffer has a minimum size of 64 samples. This can be further enlarged by setting <span class="emphasis"><em>icps</em></span> to some artificially lower pitch.
</p>
</div>
<div class="refsect1" title="Examples">
<a id="idp36574000"></a>
<h2>Examples</h2>
<p>
Here is an example of the pluck opcode. It uses the file <a class="ulink" href="examples/pluck.csd" target="_top"><em class="citetitle">pluck.csd</em></a>.
</p>
<div class="example">
<a id="idp36574968"></a>
<p class="title">
<strong>Example 598. Example of the pluck opcode.</strong>
</p>
<div class="example-contents">
<p>See the sections <a class="link" href="UsingRealTime.html" title="Real-Time Audio"><em class="citetitle">Real-time Audio</em></a> and <a class="link" href="CommandFlags.html" title="Csound command line"><em class="citetitle">Command Line Flags</em></a> for more information on using command line flags.</p>
<pre class="programlisting">
<span class="csdtag"><CsoundSynthesizer></span>
<span class="csdtag"><CsOptions></span>
<span class="comment">; Select audio/midi flags here according to platform</span>
-odac <span class="comment">;;;realtime audio out</span>
<span class="comment">;-iadc ;;;uncomment -iadc if real audio input is needed too</span>
<span class="comment">; For Non-realtime ouput leave only the line below:</span>
<span class="comment">; -o pluck.wav -W ;;; for file output any platform</span>
<span class="csdtag"></CsOptions></span>
<span class="csdtag"><CsInstruments></span>
<span class="ohdr">sr</span> <span class="op">=</span> 44100
<span class="ohdr">ksmps</span> <span class="op">=</span> 32
<span class="ohdr">nchnls</span> <span class="op">=</span> 2
<span class="ohdr">0dbfs</span> <span class="op">=</span> 1
<span class="oblock">instr</span> 1
kcps <span class="op">=</span> 220
icps <span class="op">=</span> 220
ifn <span class="op">=</span> 0
imeth <span class="op">=</span> p4
asig <span class="opc">pluck</span> 0.7, 220, 220, ifn, imeth, .1, 10
<span class="opc">outs</span> asig, asig
<span class="oblock">endin</span>
<span class="csdtag"></CsInstruments></span>
<span class="csdtag"><CsScore></span>
<span class="stamnt">i</span> 1 0 5 1
<span class="stamnt">i</span> 1 5 5 4 <span class="comment">;needs 2 extra parameters (iparm1, iparm2)</span>
<span class="stamnt">i</span> 1 10 5 6
<span class="stamnt">e</span>
<span class="csdtag"></CsScore></span>
<span class="csdtag"></CsoundSynthesizer></span>
</pre>
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